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28th January, 1904. 



Professor Johnson Symington, M.D., F.R.S., F.R.S.E. 

 President, in the Chair. 



RADIUM. 

 By John Finnegan, B.A., B.Sc. 



(Abstract.) 



The meaning of Ionisation was first explained, then the nature 

 of Kathode rays, canal rays and X-rays. Becquerel's discovery 

 that Uranium and its salts are continually emitting rays that affect 

 the photographic plate was discussed. 



After the discovery of the uranium radiation only one other 

 chemical element — thorium — was found to possess similar powers. 

 About the close of 1897 Madame Curie began the study of 

 Becquerel rays. She soon found that the emission of rays by the 

 compounds of uranium was strictly proportional to the quantity of 

 metal present, and must be an atomic property of the element 

 uranium and independent of its chemical or physical state. 



Uranium is chiefly obtained from pitchblende, a velvety black 

 mineral found in the Erzgebirge and in Cornwall. M. and 

 Madame Curie resolved to investigate the radio-activity of pitch- 

 blende, and they discovered that some specimens had a radio- 

 activity four times greater than metallic uranium itself, and they 

 immediately set about separating chemically from pitchblende one 

 substance after another, testing each portion for radio-activity. 

 In this way they discovered that, with the separate bismuth, there 





